This invention relates to a mass detector and is particularly useful in detecting whether or not a link is missing from a chain, such as a jewelry chain.
If a link is missing in a chain such as a jewelry chain, this will result in a faulty product, which is normally sold in fairly long lengths. In addition, if a link is missing, it may indicate a faulty operation of the chain-making machine. Originally, detection of a missing link was accomplished through the visual observance of an operator, and of course, was subject to human error. It also required the stationing of a person in a position to view the output of the machine. With the advent of small gold jewelry chain, it became necessary in the industry to operate the machines continuously in order to produce sufficient output for the consumer demand. Some of the devices that have been used to automatically detect a missing link in a chain have comprised a single oscillator with the chain passing through the coil that is part of the resonant circuit, which was adjusted in such a way that if a link was missing, the normally inoperative oscillator would go into oscillation and activate a visual detection and/or automatic machine-stopping mechanism. An example of a device of this general nature is seen in the Buckley et al patent, U.S. Pat. No. 3,727,075. One of the difficulties that has been found utilizing oscillators of this nature that go in and out of oscillation is that they are not stable, and the mass passing through the inductor, or the lack thereof, may not always be detected due to the inability of the oscillator to trigger itself on and off.